<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<script src="vue.js" type="text/javascript" charset="utf-8"></script>
	</head>
	<body>
		<div id="app">
			{{a}}
		</div>

		<script type="text/javascript">
			var data = {
				a: 1
			}
			var vm = new Vue({
				el: "#app",
				data: data
			})
			
			vm.$watch('a',function(newVal, oldVal){
				console.log(newVal,oldVal);
			})
			
			vm.$data.a = "test..."
			
			
		</script>

	</body>
</html>
